The present invention relates to a valve rotator for rotating a valve around a shaft gradually during operation to change engagement of a valve face with a valve seat continuously, thereby making wear of the valve face uniform
FIGS. 9 and 10 illustrate a conventional valve rotator as disclosed in Japanese Utility Mode Laid-Open Pub. No.2-110211. 1 denotes a cylinder head in an automobile engine, and 2 denotes a valve in which a valve spring 4 is provided between the cylinder head 1 and a retainer 3 of the upper end of a valve stem 2a of the valve 2. By pressing the upper end of the valve stem 2a of the valve 2 by a rocker arm 5 against upward biasing force of the valve spring 4, a valve face 2c of the lower end of the valve stem 3a is left from a valve seat 6 downwards to open a port 7.
In a conventional example as shown in FIGS. 9 and 10, the retainer 3 contains a rotator 8 for rotating the valve 2. The retainer 3 comprises a rotator body 10 which is engaged with the upper end of the valve stem 2a of the valve 2 via a cotter 9; a spring retainer 11 which is fitted under the valve body 10; a ball 12: a spring 13; a ball race 14 and a leaf spring 15. Whenever the valve 2 ascends and descends, the rotator body 10 and the spring retainer 11 are relatively rotated, thereby rotating the valve 2 gradually. The details are disclosed in Japanese Utility Model Laid-Open Pub. No.2-110211. 16 denotes a valve guide, and 17 denotes sealing material at the upper end thereof.
However, in the conventional valve rotator, it is not clear whether or not the rotator is always rotated by one vertical reciprocating movement, and how long it rotates, thereby decreasing reliability, which is disadvantageous. The structure is very complicate and assembling thereof is troublesome.